Avoid needless is_zero check in set_sign
Avoid needless is_zero check in set_sign

If not negative we don't need to check the size

webmaster128/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan,randombit/botan,webmaster128/botan,randombit/botan